Wireless communication systems have developed through various generations, including a first-generation analog wireless phone service (1G), a second-generation (2G) digital wireless phone service (including interim 2.5G and 2.75G networks) and third-generation (3G) and fourth-generation (4G) high speed data/Internet-capable wireless services. There are presently many different types of wireless communication systems in use, including Cellular and Personal Communications Service (PCS) systems. Exemplary cellular systems include the cellular Analog Advanced Mobile Phone System (AMPS), digital cellular systems based on Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), the Global System for Mobile access (GSM) variation of TDMA, and newer hybrid digital communication systems using both TDMA and CDMA technologies.
More recently, Long Term Evolution (LTE) has been developed as a wireless communications protocol for mobile phones and other terminals to communicate data at high speeds. LTE is based on GSM and includes contributions from various GSM-related protocols (e.g., Enhanced Data rates for GSM Evolution (EDGE)) and Universal Mobile Telecommunications System (UMTS) protocols (e.g., High-Speed Packet Access (HSPA)).
LTE Direct (LTE-D) is a proposed 3GPP (Release 12) device-to-device (D2D) solution for proximate discovery. LTE-D dispenses with location tracking and network calls by directly monitoring for services on other LTE-D devices within a large range (˜500 m, line of sight). Accordingly, among other advantages, LTE-D can directly monitor for services on other LTE-D devices in a synchronous system and concurrently detect potentially thousands of services in proximity in a continuous and battery efficient manner.
LTE-D operates on licensed spectrum as a service to mobile applications and provides device-to-device (D2D) solution that enables service layer discovery. Mobile applications on LTE-D devices can instruct LTE-D to monitor for mobile application services on other devices and announce their own services at the physical layer for detection by services on other LTE-D devices, which allows the applications to be closed while LTE-D does the work—continuously—and notifies the client application when a match to the monitor that was set is detected.
Accordingly, LTE-D is an attractive alternative to mobile developers seeking to deploy proximate discovery solutions to extend their existing cloud services. LTE-D is a distributed discovery solution (versus the centralized discovery that exists today), whereby mobile applications may forego centralized database processing in identifying relevancy matches. Instead, relevance may be determined autonomously at the device level by transmitting and monitoring for relevant attributes. LTE-D offers certain benefits in relation to privacy as well as power consumption, in that LTE-D does not utilize perpetual location tracking to determine proximity. By keeping discovery on the device rather than the cloud, the user has more control over what information is shared with external devices.